IgA Nephropathy

What is IgA Nephropathy (IgAN)?IgA Nephropathy, formally called Berger’s Disease, is named after the French pathologist Jean Berger (1930 – 2011) who first recognised the condition.

IgAN is a disease, which involves the immune system and the kidneys. This disease results in end-stage renal failure requiring dialysis or a kidney transplant for 25% of those affected.

One of the functions of the kidneys is to dispose of the bodies waste products by sieving the blood and producing urine. Sieves called glomeruli separate out the useful parts of the blood from the waste. There are about 1 million glomeruli per kidney.

IgA is a type of antibody, it is part of our immune system, our natural defence against infection. We have a lot of IgA in our blood, lungs and guts.

The pathway which leads to IgAN starts with the production of unusual IgA in the blood. The next step is an auto-immune response to this IgA which results in circulating IgA1 containing immune complexes. Once in the kidneys, these complexes are trapped in the glomeruli and bind to receptors on the surface of mesangial cells causing the cells to grow and make proteins; thus reducing the kidneys’ ability to carry out their filtering function. This process affects both kidneys.

SymptomsIgAN may be undetected for several years as it commonly does not cause any obvious symptoms.

When symptoms do occur they may include:

Blood in your urine (haematuria), which can either be visible to the naked eye or only detectable with a urine test. Visible haematuria often occurs when you have a sore throat, a stomach upset or after exercise.

Reduced kidney function, detectable through a blood test which will show a raised creatinine level.

Kidney function is measured using the eGFR (estimated Glomerular Filtration Rate) which is a calculated value based largely on the creatinine level in your blood. It can be useful to think of eGFR as a percentage of kidney function, an eGFR of 100 equating to 100% fully functional kidneys.

None of these symptoms prove you have IgAN. The only way IgAN can be diagnosed is through a kidney biopsy.

CausesExtensive research is being carried out into the cause(s) of IgAN.

Known factors:

The IgA molecules of IgAN patients have small but important differences in structure

There are small but important differences in the way the immune system controls the manufacture of IgA

Unknown factors:

Why the IgA sticks in the glomeruli

Why it causes much more damage to the kidneys in some people than others

Why it is more common in males

Why it is more common in some parts of the world (eg China, Japan) than others

TreatmentThere is currently no specific treatment to cure IgA nephropathy.

Clinical trials are currently underway around the world to test a number of potentially new therapies for IgAN. Over the next few years these trials should give us valuable information on how best to treat IgAN.

How does IgAN affect someone?Once IgAN is diagnosed it can be difficult to predict how or if the disease will develop. IgAN is a variable condition, a number of things may happen:

It can go away completely

It can stay the same for years

The kidneys may slowly lose function

The kidneys may fail completely

IgAN may recur after a kidney transplant

Nearly always, things happen slowly in IgAN. A kidney biopsy gives more information which may help with the prognosis and to predict what will happen to a person with IgAN.

In 2009 the Oxford Classification of IgA Nephropathy was developed to help kidney doctors decide which patients with IgAN were at risk of kidney failure and which patients might be suitable for clinical trials of new therapies.

Clinicians are getting better at predicting the progression of IgAN and considerable research is being carried out into this area.